We hypothesize that Toll like receptors play an important role in the innate immune response to KSHV infection. We have preliminary data indicating that TLR signaling is induced upon infection of monocytes with KSHV. Based on this data we propose to investigate the role of TLR signaling in KSHV infected cells, and to dissect the components of the TLR pathway that are activated in KSHV-infected monocytes. Specific Aims: 1) Determine the components of the signaling pathway induced by TLR upon infection of monocytes with KSHV;2) Study the effect of CXCL10 upregulation;3) Determine whether stimulation of TLRs 1-9 can reactivate KSHV from latently infected monocytes. Study Design: We will monitor the upregulation of the TLR signaling pathway in response to KSHV infection. Multiple cell lines will be infected with KSHV, and analyzed by qPCR. NF-KB luciferase assays will also be performed using TLR-deficient cell lines and TLR stably expressing cell lines to determine if NF-KB is specifically upregulated as a consequence of TLR activation. Cell migration assays will be employed to determine if specific downstream chemokines, upregulated in response to TLR activation, are involved in chemotaxis. Additionally, signaling mediators activated by specific TLRs will further be investigated using siRNAs to deplete specific targets prior to KSHV infection of monocytes. PUBLIC HEALTH RELEVANCE: KSHV is associated with three types of cancer in humans;Kaposi sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman's disease (MCD). These cancers are generally seen in the context of immunodeficiency but can develop in the immunocompetent host. A better understanding of the modulation of the immune system by KSHV would be of great importance considering that currently there are no vaccines or drug therapies that can cure KSHV. Cellular components that can be identified as critical to the establishment of KSHV infection could serve as possible targets for drug therapy and viral components identified as critical for KSHV infection could aid in the development of future vaccines.